The present invention relates to a touchscreen interface for a computer-based system. In particular, the present invention provides a user with the ability to reset calibration of a touchscreen to original factory calibration settings.
A touchscreen (also known as a touch panel or touchscreen panel) allows a display device such as a cathode ray tube (CRT) or liquid crystal display (LCD), to also be used as an input device. The touchscreen is typically implemented as a display device overlay that is capable of electronically recognizing changes in resistance, current, or ultrasonic waves resulting from a screen touch. These changes are programmatically converted to screen coordinates in real time, and are acted upon by the application software for which the touchscreen is providing an interface.
The translation of the electrical input produced by a screen touch to screen coordinates requires a ratio conversion calculation that relies on a baseline calibration. Generally, touchscreen interfaces will include factory default calibration settings that are stored in non-erasable memory. In addition, a software calibration routine is provided to allow user calibration to adjust for misalignment of the touchscreen with respect to the display device. This misalignment may occur due to variances in the operating environment, as well as misalignments that occurred during the manufacturing process when the touchscreen is applied to the display device. A run time calibration interface is typically provided that requires the user to make a series of two or more screen touches at specific locations that are displayed by the display device. Based upon those touches, user calibration values are derived and stored, and then used to determine the location of any screen touch.
This user calibration procedure presents the potential for inaccurate calibration if the user touches the wrong portion of the screen during the calibration process. The user calibration may then yield incorrect coordinates of screen touches when the user later attempts to use the touchscreen interface. For example, as a result of incorrect user calibration, the user may attempt to touch the screen at a location where an icon is being displayed, but the output of the touchscreen interface is inaccurate enough that the system does not recognize that touch event as occurring at the location of the icon. The system may not activate a function because of the erroneous coordinates of the touch event, or may activate a function that is different than the one the user intended.
If the user calibration is severely in error, the system may be unresponsive. For those computer-based systems which include another user input device other than the touchscreen, a recalibration of the touchscreen may still be possible. Using this other input device, the user can interact with the system and be prompted through a procedure to recalibrate the touchscreen when it malfunctions.
One of the advantages of a touchscreen interface is that it eliminates the need for a separate keyboard or other user input device. For those systems having a touchscreen interface with no other user input device, an improper or erroneous user calibration can result in rendering the touchscreen either unresponsive, or responsive in an inappropriate manner. The user may not be able to provide an input which can lead to a recalibration routine to correct the erroneous user calibration values. As a result, the system may be unusable.